voscreature

Hi,

I'm rebuilding my distributor on my 1968 427, it's a numbers correct distributor. I have bought a new mainshaft, bushings and tach side gear kit from Corvette America.

One thing I can't figure out: What is the idea of the "side gear bronze button", (part no. X2557)? That part was not in my distributor when I disassembled it. Instead, on the chewed up side gear there is a small countersunk hole, and theen a "pigtail" in the bottom of the distributor that looks like it acts as a guide to the side gear. But the CA side gear does not have the countersunk hole, instead it's a flat surface. Should I just dump the "button" or do I miss something here?

Thanks.

Martin

lars

The countersunk hole is the area that the original sidegear destroyed inside your distributor - that countersunk area is not supposed to be there. Your old gear dug itself into the housing, and this is what caused it to seize up and strip the mainshaft. The bronze button will not fit and should not be used. If you somehow make it fit, the new sidegear will chew up that bronze button within 1000 miles and destroy your distributor again.

You have to fabricate a steel insert to repair the wasted area inside the distributor. This fabricated insert needs to bring the level of the "counterbore" back to the original surface height of the inside of the housing so the new crossgear has a smooth, level thrust surface to ride against at the correct height.

See current thread on the same subject over on C1/C2 Forum:
http://forums.corvetteforum.com/c1-a...post1574326672

Lars

voscreature

Hi Lars,

Many, many thanks for your help. Now I can see more clearly.

The sole reason for the "bronze button" is to supply a budget repait kit then?

I will mill down the worn "countersunk" hole and then put in a small stainless spacer so I have a flat surface that's flush with the original surface.

One more thing I noticed on my way was the vacuum advance now when everything is disassembled. I applied vacuum from my hand pump, but the plunger does not move at all, and the vacuum is not holding for more like a 1 second. I'm not surpised though. I guess it should hold vacuum and move the plunger? Sigh...

Thanks.

lars

For most moderate performance applications, use NAPA/Echlin part number VC1765 for the vacuum advance control unit - it is readily available for about $15.

Once fabricated, you can bond the steel insert into the machined counterbore area with JBWeld. To hold it in place and assure its parallelism to the crossgear thrust surface during cure, you can put a couple of washers between the crossgear and the brass crossgear housing/bushing to extend the crossgear excessively out of the brass housing/bushing. Screw this into the distributor housing once you've bonded the new surface in and jam it down onto the new surface. This will press it into place and hold it parallel while the JBWeld cures.

Lars

voscreature

Hi Lars,

I machined a flat surface in the distributor and installed a shim with exact thickness with slight interference fit. Secured it with small tab of Loctite 603 before installation. Seems fine. Thanks for the tip.

I have received new bronze bearings also which I must replace since the original axle shaft was badly scored. Any immediate tips before I start with this? Pitfalls?

Thanks.

/Martin

lars

The only issue with installation of the shaft bushings is the bushing alignment: The lower bushing goes in just fine using the installation tool. However, the upper bushing is easily "cocked" just slightly, resulting in the mainshaft being in a bind between the two busings. I like to stick a junk shaft in from the bottom of the distributor after installing the lower bushing. This shaft will then act as a guide for the upper bushing as you knock it in. If the upper bushing does not line up just right, you can use the junk shaft inserted into the upper bushing as a lever arm to tap the upper bushing into alignment by tapping on the shaft with a rubber mallet.

Be sure to have the breaker plate slipped onto the upper bushing as you tap it into place so you drive the bushing to the correct installed height as determined by the breaker plate snap ring groove.

Lars

voscreature

Hi,

Checked the side gear installed with my new steel shim in the distrubutor housing. I think I must machine the slim very slightly as I feel some small bind on the side gear when turning by hand when I have installed the threaded brass plug all the way down. I assume it must be turning absolutely bind-free when the brass plug is tightened down making the thickness of my shim a fairly tight tolerance piece.

/Martin

lars

You can run the crossgear with a bit of endplay slop: It gets pushed into the distributor housing during operation, so the amount of play on the outside is actually fairly irrelevant as long as the distributor housing thrust surface correctly positions the crossgear centered on the mainshaft gear when the crossgear is up against the housing surface. I run mine with about .020 - .030" play. There's nothing to gain by keeping it really tight.

voscreature

Yesterday I fired up the 427 for the first time. Tachometer back in business.

Everythings seems fine, and I appreciate all helps and friendly advice in this thread.


/Martin